Alan from Hacked Gadgets wrote in with the karate chop game that he and his daughter Alexis designed.
My daughter Alexis and I worked on this Karate Chop project as an entry into the Avnet Dog Days Summer Contest. She had the idea to make a game to enter in the entertainment section of the contest. The game she came up with was a reaction game where you have to quickly move to the correct indicated position. Four infrared detection circuits was the resulting method used to detect hand movements. She also wanted to have a memory type game similar to the classic game called Simon but using the IR beams instead of buttons.